The field of art to which this invention pertains includes that of solenoid valve assemblies and particularly to diaphragm assemblies for controlling the rate of flow therethrough.
Valves are used to control the flow of fluids for various applications involved in hydraulic systems. For example, valves are used in the fuel dispensing market in order to provide and meter a proportional fluid flow of fuel One such valve is a pilot operated solenoid valve.
Typically these solenoid valves have an integrated diaphragm assembly moveable within the valve body of the solenoid valve. The diaphragm assembly is comprised of a diaphragm and a restrictor that can open and close a main passage between the solenoid valve inlet and outlet. In these designs, one side of the diaphragm is exposed to inlet fluid pressure and the opposite side of the diaphragm forms a chamber for receiving pressurized fluid. A solenoid, or alternatively an actuator, controls a pilot seal that blocks flow through a central pilot passage in the diaphragm assembly. The diaphragm assembly moves when the pressure differential acting on both sides of the diaphragm is sufficient to overcome forces, e.g. a spring, exerted on one side of the diaphragm. The diaphragm has a bleed passage allowing fluid to flow from the inlet into the chamber.
To open the valve and allow fluid to flow directly from the inlet to the outlet, the diaphragm must be moved off of a seat in the main valve body. Upon opening of the pilot passage, the main passage also opens and allows direct fluid communication between the solenoid valve inlet and outlet. It is imperative for many applications that the opening and closing of the main passage be conducted proportionally. This proportional opening and closing should be directly based on the actuation of the solenoid by the end user. It is difficult to control the proportional flow due to binding of the restrictor with the main valve body. Binding of the restrictor can cause no response after actuation or a quick response when the restrictor becomes unbound and suddenly roves.
Diaphragm assemblies having restrictor with multiple components can bind within a valve bore preventing movement of fluent movement of the diaphragm assembly. A multiple component restrictor could have a separate orifice body, flange portion, and guide portion. It is advantageous to have similar outside diameters for the flange and guide portions. When separate components are used, it is less likely that these two dimensions will be the same. Extra assembly steps are needed to sort through the component pieces in order to find components with similar dimensions. Tolerances on these parts can allow some deviance, which must coincide for all parts in order to produce a restrictor having a flange and guide with similar outer diameters. It is also much easier to manufacture the one-piece restrictor, rather than one with several pieces.
Diaphragm assemblies made of one piece can also stick within the valve bore when inlet radial fluid flow comes in contact with the guide of the restrictor. This contact can cause the restrictor to tilt relative to the longitudinal axis of the valve, and bind within the valve bore. This can occur with an open valve when the guide of the restrictor is in the radial path of the inlet fluid flow. Prior art references such as U.S. Pat. No. 5,299,775 to Kolze, U.S. Pat. No. 5,655,747 to Pasut, and U.S. Pat. No. 5,732,929 to Luppino et al. all show diaphragm assemblies with guides that come in contact with radial inlet fluid flow. These prior art designs can bind within the valve bore due to this contact.
The present invention provides a diaphragm assembly for use in a solenoid operated valve. The diaphragm assembly has a restrictor used in controlling fluid flow. The invention overcomes the obstacle of manufacturing and assembling a multiple piece restrictor and provides a single piece restrictor that controls fluid flow more proportionally.
A feature of the present invention is to provide an improved solenoid valve assembly for controlling fluid flow. The solenoid valve assembly is comprised of a valve body having an inlet and an outlet, a bore defining a main fluid passage in communication with the inlet and outlet, and a valve seat located on an innermost end of the bore between the inlet and outlet. The assembly further includes a diaphragm assembly, interposed between the valve body and a valve body cover and located between the inlet and outlet. The diaphragm assembly is engagable with the valve seat and movable for contacting the seat and closing the main fluid passage, as well as defining a chamber with the valve body. A passage within the diaphragm assembly provides fluid communication between the inlet and the chamber. A pilot passage in the diaphragm assembly provides fluid communication between the chamber and the outlet. A movable seal pad responsive to an external signal controls flow through the pilot passage. The diaphragm assembly includes the generally symmetrical fluid flow restrictor, movable within the valve body main fluid passage. The restrictor has a head portion, an intermediate portion and a guide portion surrounding a main body portion that has a pilot passage extending therethrough. The head portion has a first end of the pilot passage integrated therewith. The intermediate portion includes an annular extension with an upper side and a lower side. The guide portion has a plurality of legs radially extending from the main body portion for a distance substantially equal to the outer diameter of the annular extension. The guide portion is spaced from and interconnected with an intermediate portion by a reduced diameter gullet portion.
Another feature of the noted assembly includes having the annular extension being substantially cyclically. A further feature includes having an inwardly angled lower portion of the outer surface. Still a further feature has the longitudinal extent of the gullet portion being equal to or less than the maximum travel distance of the restrictor minus the longitudinal extent of the annular extension. Another feature includes having the head portion with a central cavity adapted for receiving an orifice body.
Still yet another feature of the noted assembly has the radial distal end portions of the plurality of legs being interconnected via a continuous, circular, annular perpheral portion. A firer feature has the annular peripheral portion having an outer diameter substantially equal to the outer diameter of the annular extension. Another feature has the outer diameter of the annular peripheral portion being slightly less than the diameter of the valve body main fluid passage.
Another attribute of the noted assembly has the diaphragm pilot passage with a diameter greater than that of the passage between the inlet and the chamber. A further attribute of the noted assembly has the main body portion, the head portion, the annular flange and the guide portion being of a one-piece construction.